#!/usr/bin/env python3

"""
    lldpmgrd

    LLDP manager daemon for SONiC

    Daemon which listens for changes in the PORT table of the State DB
    and updates LLDP configuration accordingly for that port by calling
    lldpcli.

    TODO: Also listen for changes in DEVICE_NEIGHBOR and PORT tables in
          Config DB and update LLDP config upon changes.
"""


try:
    import os
    import subprocess
    import sys
    import time

    from sonic_py_common import daemon_base
    from swsscommon import swsscommon
except ImportError as err:
    raise ImportError("%s - required module not found" % str(err))

VERSION = "1.0"

SYSLOG_IDENTIFIER = "lldpmgrd"
PORT_INIT_TIMEOUT = 300


class LldpManager(daemon_base.DaemonBase):
    """
    Class which subscribes to notifications of changes in the PORT table of
    the Redis State database and updates LLDP configuration accordingly for
    that port by calling lldpcli.
    Attributes:
        state_db: Handle to Redis State database via swsscommon lib
        config_db: Handle to Redis Config database via swsscommon lib
        pending_cmds: Dictionary where key is port name, value is pending
                      LLDP configuration command to run
    """
    REDIS_TIMEOUT_MS = 0

    def __init__(self, log_identifier):
        super(LldpManager, self).__init__(log_identifier)

        # Open a handle to the Config database
        self.config_db = swsscommon.DBConnector("CONFIG_DB",
                                                self.REDIS_TIMEOUT_MS,
                                                True)

        # Open a handle to the Application database
        self.appl_db = swsscommon.DBConnector("APPL_DB",
                                              self.REDIS_TIMEOUT_MS,
                                              True)

        self.pending_cmds = {}

    def is_port_up(self, port_name):
        """
        Determine if a port is up or down by looking into the oper-status for the port in 
        PORT TABLE in the Application DB
        """
        # Retrieve all entires for this port from the Port table
        port_table = swsscommon.Table(self.appl_db, swsscommon.APP_PORT_TABLE_NAME)
        (status, fvp) = port_table.get(port_name)
        if status:
            # Convert list of tuples to a dictionary
            port_table_dict = dict(fvp)

            # Get the oper-status for the port
            if "oper_status" in port_table_dict:
                port_oper_status = port_table_dict.get("oper_status")
                self.log_info("Port name {} oper status: {}".format(port_name, port_oper_status))
                return port_oper_status == "up"
            else:
                return False
        else:
            # Retrieve PortInitDone entry from the Port table
            (init_status, init_fvp) = port_table.get("PortInitDone")
            # The initialization procedure is done, but don't have this port entry
            if init_status:
                self.log_error("Port '{}' not found in {} table in App DB".format(
                    port_name, swsscommon.APP_PORT_TABLE_NAME))
            return False

    def generate_pending_lldp_config_cmd_for_port(self, port_name):
        """
        For port `port_name`, look up the description and alias in the Config database,
        then form the appropriate lldpcli configuration command and run it.
        """
        port_desc = None

        # Retrieve all entires for this port from the Port table
        port_table = swsscommon.Table(self.config_db, swsscommon.CFG_PORT_TABLE_NAME)
        (status, fvp) = port_table.get(port_name)
        if status:
            # Convert list of tuples to a dictionary
            port_table_dict = dict(fvp)

            # Get the port alias. If None or empty string, use port name instead
            port_alias = port_table_dict.get("alias")
            if not port_alias:
                self.log_info("Unable to retrieve port alias for port '{}'. Using port name instead.".format(port_name))
                port_alias = port_name

            # Get the port description. If None or empty string, we'll skip this configuration
            port_desc = port_table_dict.get("description")

        else:
            self.log_error("Port '{}' not found in {} table in Config DB. Using port name instead of port alias.".format(
                port_name, swsscommon.CFG_PORT_TABLE_NAME))
            port_alias = port_name

        lldpcli_cmd = "lldpcli configure ports {0} lldp portidsubtype local {1}".format(port_name, port_alias)

        # if there is a description available, also configure that
        if port_desc:
            lldpcli_cmd += " description '{}'".format(port_desc)
        else:
            self.log_info("Unable to retrieve description for port '{}'. Not adding port description".format(port_name))

        # Add the command to our dictionary of pending commands, overwriting any
        # previous pending command for this port
        self.pending_cmds[port_name] = lldpcli_cmd

    def process_pending_cmds(self):
        # List of port names (keys of elements) to delete from self.pending_cmds
        to_delete = []

        for (port_name, cmd) in self.pending_cmds.items():
            self.log_debug("Running command: '{}'".format(cmd))

            rc, stderr = run_cmd(self, cmd)

            # If the command succeeds, add the port name to our to_delete list.
            # We will delete this command from self.pending_cmds below.
            # If the command fails, log a message, but don't delete the command
            # from self.pending_cmds, so that the command will be retried the
            # next time this method is called.
            if rc == 0:
                to_delete.append(port_name)
            else:
                self.log_warning("Command failed '{}': {}".format(cmd, stderr))

        # Delete all successful commands from self.pending_cmds
        for port_name in to_delete:
            self.pending_cmds.pop(port_name, None)

    def run(self):
        """
        Subscribes to notifications of changes in the PORT table
        of the Redis Config/Application database.
        Subscribe to APP_DB - get port oper status
        Subscribe to CONFIG_DB - get notified of port config changes
        Update LLDP configuration accordingly.
        """
        self.log_info("Starting up...")

        if not os.geteuid() == 0:
            self.log_error("Must be root to run this daemon")
            print("Error: Must be root to run this daemon")
            sys.exit(1)

        # Set select timeout to 10 seconds
        SELECT_TIMEOUT_MS = 1000 * 10

        # Daemon is paused on the configuration file to avoid lldp packets with wrong information
        # until all interfaces are well configured on lldpd
        port_init_done = False
        port_config_done = False
        resume_lldp_sent = False
        start_time = time.time()

        sel = swsscommon.Select()

        # Subscribe to PORT table notifications in the Config DB
        sst_confdb = swsscommon.SubscriberStateTable(self.config_db, swsscommon.CFG_PORT_TABLE_NAME)
        sel.addSelectable(sst_confdb)

        # Subscribe to PORT table notifications in the App DB
        sst_appdb = swsscommon.SubscriberStateTable(self.appl_db, swsscommon.APP_PORT_TABLE_NAME)
        sel.addSelectable(sst_appdb)

        # Listen for changes to the PORT table in the CONFIG_DB and APP_DB
        while True:
            (state, c) = sel.select(SELECT_TIMEOUT_MS)

            if state == swsscommon.Select.OBJECT:
                (key, op, fvp) = sst_confdb.pop()
                if fvp:
                    fvp_dict = dict(fvp)

                    # handle config change
                    if ("alias" in fvp_dict or "description" in fvp_dict) and (op in ["SET", "DEL"]):
                        if self.is_port_up(key):
                            self.generate_pending_lldp_config_cmd_for_port(key)
                        else:
                            self.pending_cmds.pop(key, None)

                (key, op, fvp) = sst_appdb.pop()
                if (key != "PortInitDone") and (key != "PortConfigDone"):
                    if fvp:
                        fvp_dict = dict(fvp)

                        # handle port status change
                        if "oper_status" in fvp_dict:
                            if "up" in fvp_dict.get("oper_status"):
                                self.generate_pending_lldp_config_cmd_for_port(key)
                            else:
                                self.pending_cmds.pop(key, None)

                elif key == "PortInitDone":
                    port_init_done = True
                elif key == "PortConfigDone":
                    port_config_done = True

            # Process all pending commands
            self.process_pending_cmds()

            # Resume the daemon since all interfaces data updated and configured to the lldpd so no miss leading packets will be sent
            if not resume_lldp_sent:
                if check_timeout(self, start_time):
                    port_init_done = port_config_done = True
            if port_init_done and port_config_done:
                port_init_done = port_config_done = False
                rc, stderr = run_cmd(self, "lldpcli resume")
                if rc != 0:
                    self.log_error("Failed to resume lldpd with command: 'lldpcli resume': {}".format(stderr))
                    sys.exit(1)
                resume_lldp_sent = True

# ============================= Functions =============================


def main():
    # Instantiate a LldpManager object
    lldpmgr = LldpManager(SYSLOG_IDENTIFIER)

    # Log all messages from INFO level and higher
    lldpmgr.set_min_log_priority_info()

    lldpmgr.run()


def run_cmd(self, cmd):
    proc = subprocess.Popen(cmd, shell=True, universal_newlines=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    (stdout, stderr) = proc.communicate()
    return proc.returncode, stderr


def check_timeout(self, start_time):
    if time.time() - start_time > PORT_INIT_TIMEOUT:
        self.log_error("Port init timeout reached ({} seconds), resuming lldpd...".format(PORT_INIT_TIMEOUT))
        return True
    return False


if __name__ == "__main__":
    main()
